Sample processing apparatus, sample processing system, and method for processing sample

ABSTRACT

There is provided a VUV light processing apparatus that can apply vacuum ultraviolet light to the entire surface of a wafer in excellent reproducibility and can process the wafer with VUV (vacuum ultraviolet) light in excellent reproducibility. A VUV light processing apparatus includes: a chamber connected with a gas supply apparatus and an evacuation apparatus, the chamber being capable of reducing the pressure inside the chamber; a plasma light source that generates VUV light including a wavelength of 200 nm or less, the plasma light source including a plasma generating unit that generates plasma in the chamber; and a VUV transmission filter provided between a stage on which a sample to be processed is placed and the sample in the chamber, the VUV transmission filter transmitting the VUV light including a wavelength of 200 nm or less and not transmitting electrons, ions, and radicals in plasma, the VUV transmission filter having the outer diameter size larger than that of the sample.

TECHNICAL FIELD

The present invention relates to a sample processing apparatus, a sampleprocessing system, and a method for processing a sample, and moreparticularly to a sample processing apparatus that processes a sampleusing a VUV light (a vacuum ultraviolet light) from a plasma lightsource. The present invention further relates to a sample processingsystem and a method for processing a sample that can reduce roughness onthe side surface of pattern lines or roughness of line width using VUVlight.

BACKGROUND ART

There is being developed a VUV light (a vacuum ultraviolet light)processing apparatus that applies VUV (Vacuum Ultra-Violet) light to asample such as a semiconductor device substrate (a wafer) or the likefor processing.

A conventional VUV light (vacuum ultraviolet light) processing apparatususing an excimer lamp or the like at a wavelength of 200 nm or lessgenerally processes a wafer as described in Patent Document 1, forexample, in which a plurality of tubular excimer lamps are provided andvacuum ultraviolet light is applied to a wafer, which is a sample to beprocessed, for processing.

In such a conventional VUV light (vacuum ultraviolet light) processingapparatus using excimer lamps, cylindrical excimer lamps usingdielectric barrier discharge at a wavelength of 200 nm or less, forexample, are disposed in a lamp house. For the cylindrical excimer lamp,a Xe excimer lamp that emits excimer light at a wavelength of 172 nm isoften used. In a processing chamber, a wafer in a diameter of 300 mm,for example, which is a sample to be processed, is placed on a waferstage. Moreover, a window that can transmit vacuum ultraviolet light isdisposed between the lamp house and the processing chamber in such a waythat vacuum ultraviolet light emitted from the cylindrical excimer lampis applied to the wafer. In this case, for a window material, a flatplate made of synthetic silica that can transmit excimer light at awavelength of 172 nm, for example is used. The lamp house and theprocessing chamber are partitioned from each other by the window.

A gas inlet port and a gas outlet port are provided in the lamp house.In this case, N₂ gas is introduced, and the inside of the lamp house issubstituted with N₂, thereby suppressing the attenuation of vacuumultraviolet light due to O₂ in the air. At the same time, N₂ gas isintroduced to cool the cylindrical excimer lamps and the window formitigating a reduction in the light intensity of vacuum ultravioletlight in association with a shift of the transmission limit of vacuumultraviolet light caused by a temperature rise of synthetic silica.Similarly, a gas inlet port and a gas outlet port are also provided inthe processing chamber. In this case, N₂ gas is introduced, and theinside of the processing chamber is substituted with N₂, therebysuppressing the attenuation of vacuum ultraviolet light due to O₂ in theair.

Moreover, in another example, a vacuum outlet port provided on aprocessing chamber and a vacuum exhaust system are used to evacuate theinside of the processing chamber, and vacuum ultraviolet light isapplied to a wafer. In still another example, a vacuum outlet port and agas inlet port provided on a processing chamber, a vacuum exhaustsystem, and a gas supply system are used to evacuate the inside of theprocessing chamber, a gas is introduced into the processing chamber,and, under reduced pressure, vacuum ultraviolet light is applied to awafer.

For the applications of the VUV (Vacuum Ultraviolet light) processingapparatus, there are low-k curing, post lithography (a reduction inresist LWR after lithography, that is, VUV curing) and so on. Amongthem, for techniques related to a reduction in resist LWR, there isplasma processing using HBr plasma, N₂ plasma, or the like as in PatentDocument 2, that is, a reduction in resist LWR by plasma curing.

A technique that forms fine patterns is necessary to increase theintegration degree of semiconductor integrated circuits. Generally, inthe semiconductor manufacturing processes, photolithography techniquesare used.

In the photolithography techniques, first, a photoresist material iscoated on a thin film laminate on a semiconductor substrate, andultraviolet light or the like is applied using an exposure apparatus.Thus, circuit patterns formed on a photomask are transferred to theresist material, and the transferred resist material is furtherdeveloped.

A plasma processing apparatus is generally used for the process oftransferring the circuit patterns of the developed photoresist to underlayers of laminate thin films. The plasma processing apparatus usuallyincludes a vacuum chamber, an exhaust system that keeps the pressureinside a processing chamber formed in the vacuum chamber to apredetermined pressure, a plasma gas supply system, a wafer mountingelectrode that places and fixes a wafer thereon, and an upper electrodeincluding an antenna to generate plasma. A process gas is introducedinto the processing chamber, and glow discharge is generated in theintroduced process gas (mixed gas), thereby generating plasma. Thegenerated plasma is used to generate highly reactive radicals and ionsfor etching.

For a method of forming a fine gate electrode by etching, PatentDocument 3, for example, describes that an insulating film, a conductivelayer, and an organic material layer are formed on a semiconductorsubstrate, a first mask pattern in a mask dimension β is formed on theorganic material layer using the photolithography techniques, theorganic material layer is etched using a mixed gas of Cl₂ and O₂, thefirst mask pattern is shrunk to form a second mask pattern in a maskdimension Y (<β), the conductive layer is etched using the second maskpattern, and then a gate electrode in dimensions smaller than the maskdimension β is obtained.

Furthermore, for methods of improving the etch resistance of a resist,there is described a process in which an electron beam is applied tocure a photoresist (see Patent Document 4), or a process in which vacuumultraviolet light at a wavelength of 200 nm or less is applied to aresist pattern obtained by development for curing (see Patent Document5).

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Laid-Open Publication No.2005-158796

Patent Document 2: Japanese Patent Application Laid-Open Publication No.2008-198988

Patent Document 3: Japanese Patent Application Laid-Open Publication No.2001-308076

Patent Document 4: Japanese Patent Application Laid-Open Publication No.2003-316019

Patent Document 5: Japanese Patent Application Laid-Open Publication No.2005-197349

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

As described in Patent Document 1, it is general that a plurality oftubular excimer lamps are disposed to apply vacuum ultraviolet light toa wafer, which is a sample to be processed, and the wafer is processed.The stability and a variation over time of the light intensity ofapplied vacuum ultraviolet light were not considered sufficiently.

It is general that the lifetime of the excimer lamp is usually reducedto 75 to 50% of the initial light intensity in lighting for 1,000 to1,500 hours. Moreover, since the attenuation characteristics of thelight intensity of the excimer lamp are varied between individual lamps,in the case of disposing a plurality of tubular excimer lamps asdescribed in Patent Document 1, it is necessary to consider a variationover time of the light intensity as well as a variation over time ofwafer in-plane uniformity. However, conventionally, consideration is notsufficiently given to these points.

Under the aforementioned situations, it is shown that the cylindricalexcimer lamps and the window are not sufficiently cooled by introducingN₂ gas, and it is difficult to suppress a variation over time caused bya temperature rise of synthetic silica. Moreover, in the case of using aplurality of excimer lamps, since a variation over time is variedbetween the individual excimer lamps, it is also difficult to maintainthe uniformity of light intensity applied to a wafer. Furthermore, along-term variation over time also occurs due to a change in pressure inassociation with the leakage of a sealed gas or a temperature rise ofthe wall surface, a change in gas compositions because of a reaction orthe like between a tube wall and gas, and a change in the transmissioncharacteristics of vacuum ultraviolet light through the tube wallmaterial of the excimer lamp. Finally, the excimer lamp is usuallyreplaced when the light quantity is a certain light quantity or less. Inthe case where the excimer lamp is not replaced, the excimer lamp isoften not lit at a certain point in time. Therefore, the excimer lamp isa consumable item, causing a problem in that running costs are high.

On the other hand, plasma curing disclosed in Patent Document 2 has anexcellent reproducibility of plasma processing and a small variationover time. However, according to the study of the inventors, a change inresist pattern width (CD) after plasma curing, more particularly, adifference in CD change between a coarsely patterned portion and afinely patterned portion, that is, a difference between coarseness andfineness is increased. In other words, it is difficult that in plasmacuring, a reduction in resist LWR is not compatible with a reduction ina difference in CD between a coarse portion and a fine portion. In theinvention described in Patent Document 2, consideration is notsufficiently given to this point.

As described above, in the conventional VUV light (vacuum ultravioletlight) processing apparatus using an excimer lamp at a wavelength of 200nm or less or the like, consideration is not sufficiently given to avariation over time of the light intensity of vacuum ultraviolet lightapplied to a wafer, and there was a problem in that it is difficult toprocess wafers in excellent reproducibility.

Moreover, in the conventional plasma processing apparatus, wafers can beprocessed in excellent reproducibility. However, there was a problem inthat it is difficult to reduce a difference in CD between a coarseportion and a fine portion.

Furthermore, in the exposure process in the photolithography techniques,the improvement of resolution by shortening the wavelength of exposurelight is advancing. Dry exposure and immersion exposure by an ArF (argonfluoride) excimer laser (a wavelength of 193 nm) go mainstream insteadof a KrF (krypton fluoride) excimer laser (a wavelength of 248 nm). Infuture, double patterning techniques and EUV (Extreme Ultra Violet)exposure are scheduled.

In exposure in the photolithography techniques, it is necessary todeliver exposing light to the bottom part of a resist with sufficientintensity. However, an unnecessary portion of a photoresist material isexposed to light due to reflection at a thin film surface or irregularreflection at a step portion or the like, and ununiformity occurs inexposure. In this case, unnecessary roughness occurs on the surface orthe side surface of the circuit pattern of the photoresist formed indevelopment.

Moreover, unnecessary roughness is also formed on the surface or theside surface of the resist due to the ununiformity of resist polymersize, the aggregation of polymers, and the ununiformity of aciddiffusion in chemical amplification reactions.

Furthermore, in order to meet downscaling, the molecular structures ofphotoresist materials are improved according to exposure light sources.With this improvement, a reduction in the plasma etching resistance ofphotoresist mask patterns or the lack of the initial film thicknessbecomes a new problem.

A reduction in plasma etch resistance or the lack of the initial filmthickness causes an increase in the roughness on the line side surfaceof mask patterns (LER: Line Edge Roughness) or the roughness of linewidth (LWR: Line Width Roughness). It can be thought that thisphenomenon affects semiconductor device characteristics more than everin accelerating downscaling in future.

Moreover, when a plasma etching apparatus is used to etch under layersof laminated thin films using the photoresist circuit pattern formedwith the roughness as a mask, roughness similar to the roughness on thesurface or the side surface of the photoresist is also formed on theside surface of the etched under thin films.

It is an object of the present invention to provide a sample processingapparatus using VUV light preferably for use in applying vacuumultraviolet light to the entire surface of a wafer in excellentreproducibility and processing wafers in excellent reproducibility.

It is another object of the present invention to provide a sampleprocessing apparatus excellent in sample in-plane uniformity.

It is still another object of the present invention to provide a sampleprocessing apparatus that can improve VUV transmittance and efficientlyprocess wafers with VUV light.

Moreover, it is yet another object of the present invention to provide aplasma processing technique that can suppress roughness which occurs onthe surface or the side surface of a photoresist film formed on asemiconductor substrate in the process of forming interconnectionpatterns and can implement highly accurate etching.

Solution to Solve the Problem

In order to address the aforementioned objects, a VUV light processingapparatus according to the present invention includes: a chambersupplied with a plasma generating gas and vacuumized; a plasmagenerating space supplied with an electromagnetic wave in the chamber,the plasma generating space being formed in an upper part of thechamber; a sample stage provided in a lower part of the chamber toreceive a sample thereon; an optical filter unit including a VUVtransmission filter disposed between a plasma processing space and thestage, the stage including a sample mounting surface on which the samplebe processed is placed, and the optical filter being provided betweenthe sample stage and the plasma generating space to form the plasmaprocessing space, wherein the optical filter unit is configured toenable the processing space to communicate with an atmosphere in thechamber via a section between the stage and the VUV transmission filter.The optical filter has a function to block an ion, an electron, and aradical from entering the processing space.

Advantageous Effects of the Invention

According to the present invention, with the adoption of a plasma lightsource, there are the effects that it is possible to apply vacuumultraviolet light to the entire surface of a sample in excellentreproducibility and to process the sample with VUV light (vacuumultraviolet light) in excellent reproducibility.

Moreover, with the adoption of a plasma light source, it is possible toprovide a sample processing apparatus excellent in sample in-planeuniformity.

Furthermore, it is possible to improve VUV transmittance by reducing theplate thickness of the filter as much as possible and to efficientlyprocess wafers with VUV light.

In addition, according to the other features of the present invention,it is possible to suppress roughness that occurs on the surface or theside surface of a photoresist film formed on a semiconductor substratefor implementing highly accurate etching.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical cross sectional view illustrating a sampleprocessing apparatus with VUV light (vacuum ultraviolet light) using aneffective magnetic field microwave plasma light source according to afirst embodiment of the present invention.

FIG. 2 is a diagram illustrating the transmission characteristics of VUVlight (vacuum ultraviolet light) in the case of using synthetic silicafor a VUV transmission window (a VUV transmission filter) according tothe first embodiment.

FIG. 3 is a flowchart illustrating control performed by a controlleraccording to the first embodiment;

FIG. 4A is a diagram illustrative of the operation of the sampleprocessing apparatus according to the first embodiment.

FIG. 4B is a diagram illustrative of the operation of the sampleprocessing apparatus according to the first embodiment.

FIG. 4C is a diagram illustrative of the operation of the sampleprocessing apparatus according to the first embodiment.

FIG. 4D is a diagram illustrative of the operation of the sampleprocessing apparatus according to the first embodiment.

FIG. 5A is a diagram illustrating the VUV spectra of N and Br emittedfrom N₂ that is a plasma generating gas (plotted with reference to thedata of NIST, which is a Reference Document).

FIG. 5B is a diagram illustrating the VUV spectra of N and Br emittedfrom HBr that is a plasma generating gas (plotted with reference to thedata of NIST, which is a Reference Document).

FIG. 6 is a diagram illustrative of the processing situations of VUVcuring using a plasma light source according to an embodiment of thepresent invention.

FIG. 7A is a diagram illustrating the relationship between theaccumulated light quantity of VUV light and LWR (a change rate from theinitial LWR) in VUV curing according to an embodiment of the presentinvention.

FIG. 7B is a diagram illustrating the relationship between theaccumulated light quantity of VUV light and the CD change rates of acoarse portion and a fine portion in VUV curing according to anembodiment of the present invention.

FIG. 7C is a diagram illustrating the relationship between theaccumulated light quantity of VUV light and a difference in CD between acoarse portion and a fine portion according to an embodiment of thepresent invention based on data in FIG. 7B.

FIG. 8 is a diagram illustrative of the processing situations of VUVcuring using a plasma light source according to a comparative example.

FIG. 9A is a diagram illustrating the relationship between plasma curingtime and a resist LWR reduction rate in plasma curing according to thecomparative example;

FIG. 9B is a diagram illustrating the relationship between plasma curingtime and the CD change rates of a coarse portion and a fine portionaccording to the comparative example.

FIG. 9C is a diagram illustrating the relationship between plasma curingtime and a difference in CD between a coarse portion and a fine portionaccording to the comparative example based on data in FIG. 9B.

FIG. 10A is a vertical cross sectional view illustrating the essentialpart of a sample processing apparatus with VUV light (vacuum ultravioletlight) using an effective magnetic field microwave plasma light sourceaccording to a second embodiment of the present invention.

FIG. 10B is a diagram illustrative of the operation of the sampleprocessing apparatus according to the second embodiment.

FIG. 11 is a vertical cross sectional view illustrating a sampleprocessing apparatus with VUV light (vacuum ultraviolet light) using aneffective magnetic field microwave plasma light source according to athird embodiment of the present invention.

FIG. 12 is a flowchart illustrating control performed by a controlleraccording to the third embodiment.

FIG. 13 is a vertical cross sectional view illustrating a VUV (VacuumUltraviolet light) processing apparatus using an effective magneticfield microwave plasma light source according to a fourth embodiment ofthe present invention.

FIG. 14A is a vertical cross sectional view illustrating a VUV (VacuumUltraviolet light) processing apparatus using a cylindrical inductivelycoupled plasma (ICP) light source according to a fifth embodiment of thepresent invention.

FIG. 14B is a vertical cross sectional view illustrating a VUVtransmission filter including a VUV light intensity distributioncorrecting function according to the fifth embodiment of the presentinvention.

FIG. 15A is a vertical cross sectional view illustrating a VUV (VacuumUltraviolet light) processing apparatus using a flat inductively coupledplasma (ICP or a transformer coupled plasma TCP) light source accordingto a sixth embodiment of the present invention.

FIG. 15B is a vertical cross sectional view illustrating a VUVtransmission filter including a VUV light intensity distributioncorrecting function according to the sixth embodiment of the presentinvention.

FIG. 16 is a vertical cross sectional view illustrating a VUV (VacuumUltraviolet light) processing apparatus using a trapezoid inductivelycoupled plasma (ICP) light source according to a seventh embodiment ofthe present invention.

FIG. 17A is a vertical cross sectional view illustrating a VUVtransmission filter including a VUV light intensity distributioncorrecting function according to an eighth embodiment of the presentinvention.

FIG. 17B is an exemplary penetration pattern of light intensitycorrection penetration of the VUV transmission filter in FIG. 17A.

FIG. 18 is a diagram illustrating the schematic configuration of aplasma etching apparatus according to a ninth embodiment of the presentinvention.

FIG. 19 is a diagram illustrating an exemplary vacuum ultraviolet lightapplying unit according to the ninth embodiment.

FIG. 20 is a diagram illustrative of an etching process (a comparativeexample).

FIG. 21 is a diagram illustrative of an etching process according to atenth embodiment of the present invention. FIG. 22 is a diagramillustrating the effect of vacuum ultraviolet light applicationaccording to the tenth embodiment.

FIG. 23 is a diagram illustrative of the effect exerted on the roughnessof line width (LWR) according to the tenth embodiment.

FIG. 24A is a vertical cross sectional view illustrating the essentialpart of a sample processing apparatus with VUV light (vacuum ultravioletlight) using a plasma light source according to an eleventh embodimentof the present invention.

FIG. 24B is a diagram illustrative of the operation of the sampleprocessing apparatus according to the eleventh embodiment.

DESCRIPTION OF EMBODIMENTS

According to a representative embodiment of the present invention, asample processing apparatus includes: a chamber connected with a gassupply apparatus and an evacuation apparatus in which pressure insidethe chamber can be reduced; a plasma light source that emits VUV lightincluding a wavelength of 200 nm or less, the plasma light sourceincluding a plasma generating unit that generates plasma in a plasmagenerating space in the chamber; a VUV transmission filter providedbetween the plasma light source and a sample to be processed; the VUVtransmission filter transmits VUV light including the wavelength of 200nm or less and does not transmit electrons, ions, and radicals in theplasma; and the VUV transmission filter has the outer diameter sizelarger than that of the sample to be processed.

The aforementioned VUV transmission filter is made using syntheticsilica, MgF₂, CaF₂, LiF, sapphire, or the like, for example.

With these configurations, it is possible to provide a VUV (vacuumultraviolet) processing apparatus preferably for use in applying vacuumultraviolet light to the entire surface of the sample to be processed inexcellent reproducibility and processing the sample to be processed inexcellent reproducibility.

In the following, embodiments of the present invention will be describedin detail with reference to the drawings.

First Embodiment

A first embodiment of the present invention will be described withreference to FIGS. 1 to 9C.

First, FIG. 1 is a vertical cross sectional view illustrating a VUVlight processing apparatus using an effective magnetic field microwaveplasma light source according to the first embodiment.

In FIG. 1, 1 denotes a magnetron that generates microwaves forgenerating plasma. The microwaves are introduced into a nearlycylindrical chamber 8 through a rectangular waveguide 2, a matching unit3, a rectangular-to-circular converter 21, a circular waveguide 4, acavity resonator 5, and a silica plate 6. 7 denotes a silica showerplate disposed above the chamber 8, and a plasma generating process gassupplied from a gas pipe 9 is supplied to the chamber 8. Moreover, anevacuation apparatus 14 is connected to an exhaust duct 12 of thechamber 8 through an open and close valve 13 and an exhaust velocityvariable valve 10. A wafer mounting electrode 11, on which a wafer 15 tobe processed is placed, is provided in the lower part of the chamber 8.A VUV light processing space 16 is provided above the wafer mountingelectrode 11 so as to cover the entire wafer 15. Namely, the VUV lightprocessing space 16 is formed, which is surrounded by an annular movableside wall 27 disposed at a position to surround the wafer mountingsurface of the wafer mounting electrode 11 and an optical filter 24having the outer edge held on the movable side wall. For the opticalfilter, a VUV transmission filter 24, for example, is used. A space inthe chamber 8 and above the VUV transmission filter 24 is formed in aplasma generating space 17. Coils 18 and 19 and a yoke 20 for forming amagnetic field in the chamber 8 are disposed on the outer side of thechamber 8. Moreover, the VUV transmission filter 24 and the annularmovable side wall 27 are moved up and down by a vertical motionmechanism 28.

As described above, the VUV light processing apparatus according to thefirst embodiment includes the chamber 8 that the pressure inside thechamber can be reduced and the VUV light processing space 16 and theplasma generating space 17 formed in the chamber.

The VUV light processing apparatus according to this embodiment includesa control unit 300 including a computer (this is the same in embodimentsbelow). The control unit 300 includes a chamber internal pressureadjusting unit 301, a power supply control unit 302, a gas supplycontrol unit 303, a VUV transmission filter position control unit 304, atransfer unit 305, a wafer temperature control unit (not illustrated inthe drawing), and so on. These units are controlled by a controller 310.

The chamber internal pressure adjusting unit 301 controls the open andclose valve 13, the exhaust velocity variable valve 10, and theevacuation apparatus 14, and reduces the pressure inside the chamber 8to a predetermined vacuum degree.

The power supply control unit 302 controls the magnetron 1 to oscillatea microwave at a frequency of 2.45 GHz, and the microwave is propagatedin the rectangular waveguide 2 in a rectangular TE10 mode through anisolator (omitted in the drawing), a power monitor (omitted in thedrawing), and the matching unit 3. The microwave is propagated in thecircular waveguide 4 in a circular TE11 mode through therectangular-to-circular converter 21, propagated in the cavity resonator5, and then enters the plasma generating space 17 through the silicaplate 6 and the silica shower plate 7.

The gas supply control unit 303 always supplies a fresh gas into thechamber 8 during wafer processing. Namely, a plasma generating gascontrolled by the gas supply control unit 303 passes through the gaspipe 9 through a mass flow controller (omitted in the drawing), passesbetween the silica plate 6 and the silica shower plate 7, and isintroduced into the plasma generating space 17 in the chamber 8 throughgas holes in the silica shower plate 7. Moreover, the plasma generatingspace 17 exists in a magnetic field region generated by the coils 18 and19 and the yoke 20.

The pressure inside the chamber 8 is adjusted to a desired value usingthe exhaust velocity variable valve 10 controlled by the chamberinternal pressure adjusting unit 301, and then the plasma generating gasintroduced into the plasma generating space 17 is turned into plasma byan interaction between the microwave and the magnetic field. This plasmacontains VUV light (vacuum ultraviolet light) at a wavelength of 200 nmor more as well as a wavelength of 200 nm or less.

A fresh gas is always supplied in order to generate plasma to be aplasma light source containing VUV light (vacuum ultraviolet light). Fora gas to be supplied to the plasma generating space 17, an inert gassuch as Ar, Xe, He, Ne, or Kr, a nondepositional gas such as HBr, HCl,N₂, O₂, H₂, SF₆, NF₃, and a mixed gas of these gases are used. For anexample, a magnetic field region at a magnetic flux density of 875Gausses, in which electron cyclotron resonance (ECR) is generated with amicrowave of 2.46 GHz introduced, is formed in the plasma generatingspace 17. The magnetic field region is formed vertically to the centeraxis of the plasma generating space 17 and the introducing direction ofthe microwave and throughout the surface in the cross sectionaldirection to the center axis of the plasma generating space 17. Plasma,which is mainly generated by an interaction between the microwave of2.45 GHz and the magnetic field of 875 Gausses, emits VUV light (vacuumultraviolet light) including a wavelength of 200 nm or less to be aplasma light source.

The VUV transmission filter position control unit 304 has a function tocontrol the vertical motion mechanism 28 for the VUV transmission filter24, in which the wafer 15 is placed on the wafer mounting electrode 11,and the VUV transmission filter 24 is then lowered to almost seal theregion near the wafer 15 for a processing space, thereby roughly formingthe VUV light processing space 16. After VUV light processing, the VUVtransmission filter 24 is then lifted, and the wafer 15 is brought out.

The transfer unit 305 includes a push-up pin 53 (FIG. 4A) to deliver thewafer 15, a wafer transfer robot (not illustrated in the drawing), andso on. Moreover, a wafer fixing unit using a static vacuum mechanism(omitted in the drawing) or the like is provided on the stage 11.

The wafer temperature control unit has a function to adjust thetemperature of the wafer by controlling the circulation of a coolantusing a chiller unit (omitted in the drawing) provided on the stage 11,or by controlling a heating and cooling mechanism 50 buried with aheater.

The pressure inside the VUV light processing space 16 is reduced to alow vacuum of about 10⁻³ Pa, for example, using the evacuation apparatus14 as similar to the plasma generating space 17. The VUV transmissionfilter 24 has an outer diameter size D larger than the outer diametersize of a sample to be processed. For an example, desirably, in the casewhere the outer diameter of a sample to be processed is 300 mm, theouter diameter D of the VUV transmission filter 24 is about 350 mm, andin the case where the outer diameter of a processed sample is 450 mm,the outer diameter D of the VUV transmission filter 24 is about 500 mm.Moreover, the VUV transmission filter 24 does not transmit electrons,ions, and radicals in plasma, and transmits only photons, that is, VUVlight (vacuum ultraviolet light) including a wavelength of 200 nm orless. This VUV transmission filter is made of synthetic silica, MgF₂,CaF₂, LiF, sapphire, or the like, for example. Thus, only VUV light(vacuum ultraviolet light) from the plasma light source is applied tothe sample 15 to be processed, which is located on the stage 11 in theVUV light processing space 16. Furthermore, for the thickness of the VUVtransmission filter, in other words, the strength of the VUVtransmission filter, it is sufficient that the VUV transmission filtercan hold a pressure difference between both surfaces of the VUVtransmission filter and the weight of the VUV transmission filter itselfat the outer edge.

Namely, the plate thickness of the VUV transmission filter 24 isrestricted by the pressure difference between the plasma generatingspace 17 and the VUV light processing space 16 and the diameter of theVUV transmission filter 24. The smaller the plate thickness of the VUVtransmission filter 24 is, the more increased the VUV transmittance ofthe VUV transmission filter 24 is. In the present invention, since thepressure inside the VUV light processing space 16 is reduced by the sameevacuation apparatus 14 for the plasma generating space 17, a pressuredifference to act on the upper and lower surfaces of the VUVtransmission filter is small. Thus, even though the outer diameter ofthe wafer is large, it is possible to improve VUV transmittance byreducing the plate thickness of the VUV transmission filter as much aspossible and to efficiently process the wafer 15 with VUV light.

It is noted that desirably, a high heat transfer material such asaluminum and ceramics is used for the base material of the annularmovable side wall 27, and the outer side of the annular movable sidewall 27 is coated or covered with a material such as silica glass thatdoes not tend to be a contamination source due to plasma sputtering orthe like. Thus, the heat of the VUV transmission filter received fromplasma can be conducted to the stage 11 through the annular movable sidewall 27.

The plasma generating space 17 is necessary to have a height H1 enoughto generate plasma by electron cyclotron resonance. On the other hand,desirably, a height H2 of the VUV light processing space 16 is reducedas low as possible in a range in which there is no possibility that theVUV transmission filter does not contact with the sample 15 to beprocessed due to the deformation of the VUV transmission filter, inorder to reduce the possibility of entry of electrons, ions, andradicals in plasma from the plasma generating space 17. In the presentinvention, the amount of deformation of the VUV transmission filtercaused by the pressure difference to act on the upper and lower surfacesof the VUV transmission filter is small, which is ignorable. Thus, eventhough the outer diameter of the wafer or the filter is large, theheight H2 of the VUV light processing space 16 can be minute. Morespecifically, desirably, the height H2 of the VUV light processing space16 is about 5% of the outer diameter D of the filter or less. Thepossibility of entry of electrons, ions, and radicals in plasma into theVUV light processing space 16 can be more reduced as the height H2 ismade smaller. It is noted that desirably, the lower limit of the heightH2 is the height that causes no problem on the operation of the transferarm of the transfer unit 305. Moreover, desirably, the height H1 rangesfrom about 300 to 500 mm.

The VUV light (vacuum ultraviolet light) emitted from plasma generatedin the aforementioned plasma generating space 17 is varied depending ona gas to be introduced, pressure, microwave output, magnetic fieldconditions, or the like.

FIG. 2 illustrates VUV light (vacuum ultraviolet light) transmissioncharacteristics in the case of using synthetic silica for the VUVtransmission filter 24. In this case, roughly, VUV light at a wavelengthof 160 nm or more can be transmitted. In future, it is also expectedthat an optical filter having the lower limit at a wavelength of about150 nm is developed. The diameter of the VUV transmission filter 24 islarger than the diameter of the wafer 15. Thus, it is possible to applyVUV light (vacuum ultraviolet light) emitted from the plasma generatingspace and transmitted through the VUV transmission filter 24 to theentire surface of the wafer 15 for VUV light processing.

FIG. 3 is a flowchart illustrating control performed by the controlleraccording to the first embodiment. The operation of the sampleprocessing apparatus according to the first embodiment will be describedwith reference to FIGS. 4A to 4D.

First, the VUV transmission filter 24 and the annular movable side wall27 are provided with the vertical motion mechanism 28 to lift the VUVtransmission filter 24 and the annular movable side wall 27 topredetermined positions as illustrated in FIG. 4A (S301). The pressureinside the chamber 8 is then reduced to a high vacuum degree of about10⁻³ Pa, for example. Thus, remaining gas and foreign substances in thechamber 8 are discharged (S302). It is noted that this evacuation iscontinued until the processing of all wafers is completed. Subsequently,one wafer to be processed is brought in the chamber (S303). Asillustrated in FIG. 4B, the wafer 15 is placed on the wafer mountingelectrode 11, and fixed by electrostatic chucking. It is then confirmedthat the pressure inside the chamber 8 is sufficiently reduced to a highvacuum degree of 10⁻³ Pa or less, for example (S304). In the state inwhich the pressure is reduced, the VUV transmission filter 24 and theannular movable side wall 27 are lowered to roughly seal the region nearthe wafer 15, thereby forming the VUV light processing space 16 (S305).In this formation, the pressures in the VUV light processing space 16and the plasma generating space 17 are substantially the same pressure(P16=P17). It is noted that the evacuation in the processing space maybe continued as similar to the plasma generating space as necessary alsoafter sealing. Subsequently, a plasma generating process gas isintroduced into the chamber 8 (S306). The order of steps S305 and S306may be reversed. Although it is likely that a slight amount of processgas is mixed into the processing space 16, it is sufficient that themagnetic field conditions are controlled so as not to bring the ECRsurface in the VUV light processing space 16 for suppressing thegeneration of plasma in the VUV light processing space.

The exhaust velocity variable valve 10 adjusts the pressure inside thechamber 8 (S307). Thus, the pressure inside the chamber 8 is adjusted toa pressure of about 1 to 10 Pa, for example, suited for generatingplasma in the plasma generating space 17.

Subsequently, as illustrated in FIG. 4C, microwaves are supplied intothe chamber 8 to generate plasma in the plasma generating space 17(S308). This plasma is used for a light source, and only VUV light inthis plasma light source is applied to the wafer through the VUVtransmission filter 24 for curing the wafer. After finishing VUV lightprocessing, generating plasma in the chamber 8 is turned off (S309), andintroducing gas into the chamber 8 is also turned off (S310). Moreover,adjusting the pressure inside the chamber is also turned off (thevariable valve is fully opened) (S311).

After processing the wafer with VUV light, as illustrated in FIG. 4D,the VUV transmission filter 24 and the annular movable side wall 27 arelifted between predetermined positions (S312), and the wafer 15 isbrought out of the chamber 8 (S313). Subsequently, the similar processesare repeated until the VUV light processing of all wafers to beprocessed is completed (from S303 to S314). After the completion of VUVlight processing, the VUV transmission filter 24 and the annular movableside wall 27 are lowered to the positions in the initial state (S315),and the process is ended.

FIGS. 5A and 5B illustrate the VUV spectra of N and Br emitted using atypical process gas, N₂, HBr, or the like (plotted with reference to thenumeric value data of NIST, which is a Reference Document). The VUVlight in the plasma light source contains various wavelengths. With theVUV transmission filter 24 using synthetic silica, VUV light roughly atwavelengths of 200 to 160 nm can be used for processing.

Moreover, a gas is sealed in a lamp in a conventionally known excimerlamp. However, in the case of the plasma light source according to thepresent invention, a fresh gas is always stably supplied to the plasmagenerating space through the mass flow controller (omitted in thedrawing) when processing the wafer 15. Thus, there is the effect that itis possible to emit VUV light (vacuum ultraviolet light) in excellentreproducibility and to process the wafer 15 with VUV light in excellentreproducibility.

Furthermore, it is made possible to reduce a difference in CD between acoarse portion and a fine portion using the plasma light sourceaccording to the present invention. In the following, this point will bedescribed.

One of applications of VUV light processing is VUV curing. Theaforementioned VUV light (vacuum ultraviolet light) is applied to apatterned resist as a fine patterning mask on the wafer 15. First, theprocess situations of VUV curing using the plasma light source accordingto the embodiment of the present invention will be described withreference to FIG. 6. FIG. 6 is a diagram illustrating the crosssectional structure of a sample 70 to be processed (a well known finegate electrode formed on a semiconductor substrate 76 including aninsulating file 75, a conductive layer 74, a mask layer 73, and ananti-reflective film 72 and a photoresist mask pattern 71). According tothe present invention, since the VUV transmission filter transmits onlyphotons, there is the effect that it is possible to perform uniformprocessing to reduce resist LWR, regardless of how coarse or fine thepattern is, even in the case where a fine patterning mask 71 hascoarsely patterned portions and finely patterned portions 77 asillustrated in FIG. 6.

FIG. 7A illustrates the relationship between the accumulated lightquantity of VUV light and LWR (a change rate from the initial LWR) inthe present invention. Moreover, FIG. 7B illustrates the relationshipbetween the accumulated light quantity of VUV light and the CD changerates of a coarsely patterned portion and a finely patterned portion.Furthermore, FIG. 7C illustrates the relationship between theaccumulated light quantity of VUV light and a difference in CD between acoarse portion and a fine portion in the embodiment of the presentinvention based on data in FIG. 7B.

As illustrated in FIG. 7A, it is revealed that the resist LWR issuddenly reduced upon applying VUV light and reduced to 50% of theinitial LWR. Moreover, it is apparent from FIGS. 7B and 7C that thepresent invention exerts the effect of suppressing a pattern CDdifference between a coarse portion and a fine portion.

Moreover, in the case of the plasma processing apparatus according tothe present invention, a gas is introduced during plasma processing, andthe pressure inside the VUV light processing space is adjusted to beconstant for evacuating the gas. Thus, the reproducibility of plasmaprocessing is excellent, and a variation over time is small.

For a comparative example, the process situations of VUV curing using aplasma light source without a VUV transmission filter will be describedwith reference to FIG. 8. Moreover, FIG. 9A illustrates the relationshipbetween plasma curing time and a resist LWR reduction rate in plasmacuring. FIG. 9B illustrates the relationship between plasma curing timeand the CD change rates of a coarse portion and a fine portion. FIG. 9Cillustrates the relationship between plasma curing time and a CDdifference between a coarse portion and a fine portion based on data inFIG. 9B. As illustrated in FIG. 9A, although the effect of reducingresist LWR is obtained by plasma curing, a difference in CD between acoarse portion and a fine portion is increased. According to a resultstudied by the inventors, this is because a factor can be consideredthat probabilities are different between a coarsely patterned portionand a finely patterned portion to which radicals generated by plasmaenter as illustrated in FIG. 8.

According to the present invention, as illustrated in FIGS. 7B and 7C,in the case of VUV curing, there is the effect that a CD differencebetween a coarse portion and a fine portion does not occur because CDdoes not change in both a coarsely patterned portion and a finelypatterned portion by VUV application. Moreover, there is no differencein CD between a coarse portion and a fine portion, and resist LWR can bereduced. Thus, in the case where a resist after VUV curing is used as amask to etch a base film (BARC, SiON, amorphous carbon, spin-on carbon,SiO₂, SiN, poly-Si, metal material, a Si substrate, or the like, forexample) after VUV application, there is a merit that it is possible toreduce LWR after processed and to reduce a difference in CD between acoarse portion and a fine portion.

In the example described above, a dry ArF resist and an immersion ArFresist were used for a resist. The similar effect was confirmed also inan EUV resist used for much finer patterning. Particularly in the EUVresist, since the ratio of LWR to CD is large because of downscaling, areduction in LWR by VUV curing is significantly useful. This is becausea reduction in LWR relates to a reduction in fluctuations of electricalcharacteristics of a device after etched.

VUV curing is that VUV light (vacuum ultraviolet light) is applied to anArF resist or the like to dissociate, split, and desorb a carbonylgroup, a lactone group, or the like for changing the structure of theresist, and micro reflow is generated on the resist surface forsmoothing the resist surface. This is a so-called photochemicalreaction, and wafer temperature is also an important parameter.Particularly, the glass transition temperature of the resist relates tosoftening the resist and micro reflow. Thus, as illustrated in FIG. 1,there is the effect that increases LWR reducing effect or that improvesthe reproducibility of wafer processing by controlling wafer temperatureusing the wafer temperature control unit such as the heating and coolingmechanism 50 provided on the wafer mounting electrode 11.

As described above, according to the present invention, with theadoption of the plasma light source, there are the effects that it ispossible to apply vacuum ultraviolet light to the entire surface of thesample in excellent reproducibility and to process the sample with VUVlight (vacuum ultraviolet light) in excellent reproducibility. Moreover,with the adoption of the plasma light source, it is possible to providea sample processing apparatus excellent in sample in-plane uniformity.

Furthermore, according to the present invention, since the inside of thechamber is vacuumized in a state in which the VUV light processing spaceis communicated with the plasma generating space, it is possible toreduce a pressure difference between the plasma generating space and theVUV light processing space in the process of evacuation or the like, andit is possible to secure necessary strength even though the platethickness of the VUV transmission filter is reduced. Thus, there are theeffects that the plate thickness of the VUV transmission filter is thineven though the outer diameter of the wafer is large, that VUV light(vacuum ultraviolet light) transmitted through the VUV transmissionfilter is increased, and that the VUV light processing velocity of thewafer is increased.

Second Embodiment

In the first embodiment, the VUV light processing space 16 is vacuumizedfor VUV light processing. However, a gas that does not absorb VUV lightsuch as N₂ and a noble gas, for example, may be introduced as a secondgas into the VUV light processing space 16 from the gas inlet port 26through the mass flow controller (omitted in the drawing) forprocessing.

A second embodiment of the present invention will be described withreference to FIGS. 10A and 10B. A gas inlet port 26 and a gas outletport 25 are provided in order to supply a second gas into a region nearthe outer rim of the wafer 15 in the processing space 16. It issufficient that the timing of supplying the second gas into the VUVlight processing space 16 is almost the same as the timing at which aplasma generating process gas is introduced into the chamber 8 (S306 inFIG. 3), and the introduction of the gas is stopped (S310).

In the case where the second gas is N₂, the VUV light processing effectalmost similar to the VUV light processing effect in a vacuum can beobtained. In this case, the pressure inside the VUV light processingspace 16 may be adjusted using the vacuum pump 14 and the exhaustvelocity variable valve 10. Namely, the pressure inside the VUV lightprocessing space 16 may be adjusted as similar to adjusting the pressureinside the chamber 8 (S307 and S311 in FIG. 3). In the case of providinga simple configuration, such a structure may be possible in which theintroduced gas is discharged from a gas outlet port (omitted in thedrawing) without the vacuum pump 14 and the exhaust velocity variablevalve 10.

Moreover, desirably, a pressure adjusting mechanism (omitted in thedrawing) is provided so as to minimize a pressure difference between theplasma generating space 17 and the VUV light processing space 16. Asdescribed above, the plate thickness of the VUV transmission filter 24is restricted by the pressure difference between the plasma generatingspace 17 and the VUV light processing space 16 and the diameter of theVUV transmission filter 24. The VUV transmittance of the VUVtransmission filter 24 is more increased as the plate thickness of theVUV transmission filter 24 is smaller, so that it is possible toefficiently process the wafer 15 with VUV light.

Furthermore, such a configuration may be possible in which a reactivegas (a process gas) such as SF₆, Cl₂, HBr, O₂, or CF₄ is introduced intothe VUV light processing space 16 from the gas inlet port 26 through amass flow controller (omitted in the drawing) and the pressure insidethe VUV light processing space 16 is adjusted using the vacuum pump 14and the exhaust velocity variable valve 10 for processing the wafer 15.In this case, VUV light (vacuum ultraviolet light) is applied to causethe molecules of the reactive gas to be excited or dissociated for aphoto excited state reaction with the wafer 15, or alternatively, themolecules of the reactive gas are attached to the surface of the wafer15, and VUV light (vacuum ultraviolet light) is applied to the attachedmolecules for a photo surface excited state reaction, whereby the wafer15 can be processed.

According to this embodiment, with the adoption of the plasma lightsource, it is possible to apply vacuum ultraviolet light to the entiresurface of the sample in excellent reproducibility and to process thesample with VUV light in excellent reproducibility. Moreover, with theadoption of the plasma light source, it is possible to provide a sampleprocessing apparatus excellent in sample in-plane uniformity.Furthermore, it is possible to improve VUV transmittance by reducing theplate thickness of the filter as much as possible and to efficientlyprocess wafers with VUV light.

For the application of this embodiment, there is resist trimming inwhich the resist CD (the pattern critical dimension) is narrowed to adesired value while reducing resist LWR.

Third Embodiment

A third embodiment of the present invention will be described withreference to FIGS. 11 and 12.

In this embodiment, the VUV transmission filter 24 and a thin,ring-shaped filter holder 54 are disposed right above the wafer 15,instead of covering the region around the wafer 15 with the VUVtransmission filter 24 and the annular movable side wall 27 in the firstembodiment illustrated in FIG. 1. Since the filter holder 54 and thevertical motion mechanism 28 are exposed to plasma, desirably, a highheat transfer material such as aluminum and ceramics is used for thebase material of the filter holder 54 and the vertical motion mechanism28, and the outer side of the filter holder 54 and the vertical motionmechanism 28 is coated or covered with a material such as silica glassthat does not tend to be a contamination source due to plasma sputteringor the like.

Although the point in that the positions of the VUV transmission filter24 and the filter holder 54 are controlled by the vertical motionmechanism 28 of the VUV transmission filter position control unit 304 isthe same as in the first embodiment, the second embodiment is differentin that the plasma generating space 17 and the VUV light processingspace 16 are two spaces always in a communicating state. As same as thesecond embodiment, a gas inlet port 26 and a gas outlet port 25 areprovided.

It is noted that desirably, the height H2 of the VUV light processingspace 16 is about 5% of the outer diameter D of the filter or less assimilar to the first embodiment. The possibility of entry of electrons,ions, and radicals in plasma into the VUV light processing space 16 canbe more reduced as the height H2 is made smaller.

FIG. 12 is a flowchart illustrating control performed by a controlleraccording to the third embodiment. In the following, the operation of asample processing apparatus according to this embodiment will bedescribed.

First, the inside of a chamber is evacuated (S1201). This evacuation iscontinued until the processing of all wafers is completed. The filterholder 54 is provided with the vertical motion mechanism 28 to lift theVUV transmission filter 24 to a predetermined position (S1202). Asdifferent from the first embodiment, since the processing space 16 andthe plasma space 17 are not isolated from each other in startingprocessing, the timing of starting the first evacuation is notrestricted by the position of the VUV transmission filter 24.Subsequently, a wafer is then brought in the chamber (S1203), and thewafer 15 is placed on a wafer mounting electrode 11. Then, in a state inwhich the pressure inside the chamber 8 is sufficiently reduced, thevertical motion mechanism 28 lowers the VUV transmission filter 24 toform the upper space of the region near the wafer 15 to be the VUV lightprocessing space 16. The pressures in the VUV light processing space 16and the plasma generating space are the same pressure. Subsequently, aplasma generating process gas is introduced into the chamber (S1205). Inorder to suppress the entry of radicals or the like from the plasmagenerating space 17, a third gas is introduced into the region aroundthe wafer in the processing space 16 (S1206). The pressure inside thechamber 8 is adjusted using a variable valve (S1207). Subsequently,microwaves are supplied into the chamber 8 to generate plasma (S1208).VUV light in this plasma is applied to the wafer for curing the wafer.After finishing VUV light processing, generating plasma in the chamberis turned off (S1209), and introducing the process gas into the chamberis also turned off (S1210). Moreover, introducing the third gas isturned off (S1211), and adjusting the pressure inside the chamber isalso turned off (the variable valve is fully opened) (S1212).

After VUV light processing, the vertical motion mechanism 28 lifts theVUV transmission filter 24 to a predetermined position (S1213), and thewafer 15 is brought out (S1214). Subsequently, the similar processes arerepeated until the VUV light processing of all wafers to be processed iscompleted (S1203 to S1215). After the completion of VUV lightprocessing, the VUV transmission filter 24 and the filter holder 54 arelowered to the positions in the initial state (S1216), and the processis ended.

In this embodiment, since the plasma generating space 17 communicateswith the VUV light processing space 16, it is possible to reduce apressure difference between the two spaces 16 and 17, exerting thesimilar effect as in the first and second embodiments.

Moreover, introducing a gas such as N₂ and a noble gas that does nottransmit VUV light from the gas inlet port 26 near the wafer 15 cansuppress the entry of radicals that are generated in the plasmagenerating space 17 into the VUV light processing space 16. Thus, thereis the effect that it is possible to suppress the pattern CD differencebetween a coarse portion and a fine portion caused by plasma curingdescribed above.

It is noted that the VUV transmission filter 24 may be exchanged using awafer transfer robot (omitted in the drawing) or the like.Alternatively, a holder (omitted in the drawing) that can hold aplurality of the VUV transmission filters 24 therein may be disposed toexchange the VUV transmission filter 24. These methods make the VUVtransmission filter 24 exchangeable, whereby the VUV transmission filter24 can be exchanged without exposing the VUV transmission filter 24 toair even in the case where the VUV light transmission characteristicsare degraded due to the contamination or the like of the VUVtransmission filter 24. Thus, there is the effect that it is possible toimprove throughput and to process the wafer 15 with VUV light inexcellent reproducibility.

Fourth Embodiment

A fourth embodiment of the present invention will be described withreference to FIG. 13.

In the third embodiment, in the case where the distance between the VUVtransmission filter 24 and the wafer mounting electrode 11 is sufficientfor a wafer transfer robot or the like to place, bring out, and so onthe wafer 15, the vertical motion mechanism 28 for the VUV transmissionfilter 24 may be omitted. Namely, in the case where a distance H3(corresponding to the upper limit of H2) between the VUV transmissionfilter 24 and the wafer mounting electrode 11 is the height sufficientfor the wafer transfer robot or the like to place, bring out, and so onthe wafer 15, such a configuration may be possible in which a thin,ring-shaped filter holder 56 is fixed to the wafer mounting electrode 11using a plurality of narrow poles 57 and the vertical motion mechanism28 for the VUV transmission filter 24 is omitted. It is without sayingthat the positions of the poles 57 are positions to cause no problem tobring in and out the wafer 15. Since the filter holder 56 and thevertical motion mechanism 28 are exposed to plasma, desirably, a highheat transfer material such as aluminum and ceramics is used for thebase material of the filter holder 56 and the vertical motion mechanism28, and the outer side of the filter holder 56 and the vertical motionmechanism 28 is coated or covered with a material such as silica glassthat does not tend to be a contamination source due to plasma sputteringor the like.

The operation of this embodiment is as the flowchart of the thirdembodiment except that the vertical motion mechanism 28 moves up anddown the VUV transmission filter 24.

Also in this embodiment, with the adoption of the plasma light source,it is possible to apply vacuum ultraviolet light to the entire surfaceof the sample in excellent reproducibility and to process the samplewith VUV light in excellent reproducibility. Moreover, with the adoptionof the plasma light source, it is possible to provide a sampleprocessing apparatus excellent in sample in-plane uniformity.Furthermore, it is possible to improve VUV transmittance by reducing theplate thickness of the filter as much as possible and to efficientlyprocess wafers with VUV light.

Fifth Embodiment

A fifth embodiment of the present invention will be described withreference to FIGS. 14A and 14B.

This embodiment uses a cylindrical inductively coupled plasma (ICP)source as illustrated in FIG. 14A, instead of using the effectivemagnetic field microwave plasma source for the plasma light source inthe third embodiment illustrated in FIG. 11. In FIG. 14A, 29 denotes ahigh frequency power supply, 30 denotes a high frequency coil, 31denotes a shield cover, 32 denotes a processing gas supply source, and36 denotes a gas pipe. In a nearly cylindrical chamber 8 that thepressure inside the chamber can be reduced, there are the plasmagenerating space 17 and the VUV light processing space 16 locatedtherebelow, and a VUV transmission filter 24A is disposed between thetwo spaces. The configuration of the VUV light processing space 16 isthe same as in the third embodiment.

Also in this embodiment, there are the similar effect and operation asin the third embodiment.

It is noted that in this embodiment, the VUV light intensitydistribution of the plasma light source tends to be concave. Thus, it issufficient that the longitudinal section of the VUV transmission filter24A is also formed in a concave shape as illustrated in FIG. 14B.Therefore, there is the effect that the VUV light intensity distributionapplied to the wafer 15 from the plasma light source through the VUVtransmission filter 24A is corrected to be uniform, whereby it ispossible to uniformly process the wafer 15 with VUV light.

Sixth Embodiment

A sixth embodiment of the present invention will be described withreference to FIGS. 15A and 15B.

This embodiment uses a flat inductively coupled plasma (ICP or TCP)source as illustrated in FIG. 15A, instead of using the effectivemagnetic field microwave plasma source for the plasma light source inthe embodiment illustrated in FIG. 11.

In FIG. 15A, 29A denotes a first high frequency power supply thatsupplies electric power to a coil 33A on the inner side, 29B denotes asecond high frequency power supply that supplies electric power to acoil 33B on the outer side, 34 denotes a shield cover, and 35 denotes agas pipe. In the nearly cylindrical chamber 8 that the pressure insidethe chamber can be reduced, there are the plasma generating space 17 andthe VUV light processing space 16 located therebelow, and a VUVtransmission filter 24B is disposed between the two spaces. Theconfiguration of the VUV light processing space 16 is the same as in thethird embodiment.

Also in this embodiment, there are the similar effect and operation asin the third embodiment.

Moreover, in this embodiment, electric power supplied from the firsthigh frequency power supply 30 and the second high frequency powersupply 30 causes the VUV light intensity distribution of the plasmalight source to be convex, flat, or concave. It is sufficient that theplate thickness of the VUV transmission filter 24B is changed accordingto the VUV light intensity distribution of the plasma light source.

Generally, VUV light absorption is more increased as the plate thicknessof the VUV transmission filter 24B is thicker, and VUV light isattenuated (in detail, it is necessary to consider multiple reflectionor the like on both front and back surfaces). Therefore, in the casewhere the VUV light intensity distribution of the plasma light source isconvex, the cross section of the VUV transmission filter 24B is madeconvex as illustrated in FIG. 15B, whereby it is possible to correct theVUV light intensity distribution to be uniform, which is applied to thewafer 15. In the case where the VUV light intensity distribution isconcave, it is sufficient that the VUV transmission filter 24A asillustrated in FIG. 14B is adopted to correct the VUV light intensitydistribution to be uniform. As described above, it is possible touniformly process the wafer 15 with VUV light.

Seventh Embodiment

A seventh embodiment of the present invention will be described withreference to FIG. 16.

This embodiment uses a trapezoid inductively coupled (ICP) plasma sourceas illustrated in FIG. 16, instead of using the effective magnetic fieldmicrowave plasma source for the plasma light source in the embodimentillustrated in FIG. 11.

In FIG. 16, 36 denotes a gas pipe, 37 denotes a first high frequencypower supply that supplies electric power to a coil 41 on the lowerside, 38 denotes a second high frequency power supply that supplieselectric power to a coil 42 on the upper side, and 39 and 40 denote ashield cover. In the chamber 8 of nearly truncated cone shaped, whereinthe pressure inside the chamber can be reduced, there are the plasmagenerating space 17 and the VUV light processing space 16 locatedtherebelow, and a VUV transmission filter 24C is disposed between thetwo spaces. The configuration of the VUV light processing space 16 isthe same as in the third embodiment. It is sufficient that the shape ofthe VUV transmission filter 24C is appropriately selected according tothe VUV light intensity distribution of the plasma light source.

Also in this embodiment, there are the similar effect and operation asin the third embodiment.

In addition to this, the similar effect and operation can be exertedalso using a surface wave plasma source, a parallel plate plasma source,a magnetron discharge plasma source, a dielectric barrier dischargeplasma source, or the like.

In the plasma sources described above, plasma uniformity is varieddepending on the conditions such as gas species, pressure, a flow rate,a magnetic field, and microwave (high frequency) electric power.Accordingly, the uniformity of VUV light (vacuum ultraviolet light) isvaried, which is emitted from the plasma light source, transmittedthrough the VUV transmission filter 24, and applied to the wafer 15, sothat the plasma conditions described above are optimized. In the case ofthe effective magnetic field microwave plasma source in FIGS. 1 to 12,the conditions of a magnetic field and microwave output are oftenchanged. In the case of inductively coupled plasma (ICP) discharge usingtwo power supplies in FIGS. 15A and 16, the input electric power of thetwo power supplies and the ratio between the power supplies are oftenchanged.

Eighth Embodiment

An eighth embodiment of the present invention will be described withreference to FIGS. 17A and 17B.

In this embodiment, alight intensity correction through plate 60 that anaperture ratio is changed in the plane as illustrated in FIG. 17B and acover 61 that covers two surfaces of the plate 60 with a VUVtransmission material as illustrated in FIG. 17A are provided, insteadof changing the plate thickness of the VUV transmission filter 24Caccording to the VUV light intensity distribution of the plasma lightsource in the seventh embodiment, for example. The light intensitycorrection through plate 60 is made of a material that does not transmitVUV light such as a metal plate, a ceramics plate, a glass plate, and aSi plate. In this embodiment, a thin stainless steel plate was used.Moreover, the in-plane distribution (the aperture ratio) of the throughpart is changed so as to provide a desired in-plane light intensitydistribution using a plurality of openings, that is, a through meshstructure or a structure with a large number of through holes, therebycorrecting the in-plane light intensity distribution of VUV light.

In this embodiment, the pattern is a radial pattern as illustrated inFIG. 17B. The pattern may be any given patterns according to the lightintensity distribution of the plasma light source such as a mesh patternand a dot pattern with holes, for example. The cover 61 made of a VUVtransmission material has the effect that suppresses contamination orthe like due to sputtering, reactions, or the like caused by plasma orthe like. This embodiment has the effect and operation similar to theseventh embodiment.

Moreover, such a configuration may be possible in which the VUV lightintensity distribution correcting unit in the fifth to seventhembodiments of the present invention can be exchanged using a wafertransfer robot (omitted in the drawing) or the like as similar to theVUV transmission filter 24 (24A to 24C) described above. Thus, there isthe effect that it is possible to perform VUV light processing with adesired VUV light intensity distribution according to the wafer 15,which is a sample to be processed.

Furthermore, for the application of the embodiment described above, thisembodiment is applicable to removing organic contamination on a wafer ora photomask, low-k film curing, a reduction in LWR of a resist pattern,suppressing CD fluctuations in a resist pattern caused by electrons orthe like, resist trimming (CD control), and so on. In addition to this,the present invention is applicable to any applications in which VUVlight (vacuum ultraviolet light) is applied to a sample to be processedsuch as a wafer and the sample is processed, exerting the similar effectand operation.

Ninth Embodiment

Next, the application of the VUV light (vacuum ultraviolet light)processing apparatus will be described. As described above, when theplasma etching apparatus is used to etch laminated under thin films withthe photoresist circuit pattern formed with the roughness as a mask,roughness similar to the roughness on the surface or the side surface ofthe photoresist is also formed on the side surface of the etched underthin films.

Moreover, the roughness on the surface or the side surface of thisphotoresist sometimes grows due to etching the resist or the depositionof reaction products in the process of etching.

For example, in processing a gate electrode of a MOS transistor,roughness on the photoresist surface is transferred to the side surfaceof a polysilicon layer, and gate electrode with a roughness of a fewnanometers is formed. Since the gate length is reduced to a few tensnanometers with the downscaling of LSI (Large Scale Integration), theroughness of the order of a few nanometers greatly affects thecharacteristics of the MOS transistor. For the influence on the actualdevice characteristics, the roughness of a few nanometers on the sidesurface of the polysilicon layer causes a short channel effect, leadingto an increase in a leakage current or a reduction in threshold voltage.Moreover, the roughness of a few nanometers on the side surface of apositive silicon layer causes variations in the gate length each oftransistors, leading to a reduction in yields on the performance oftransistors.

A problem of roughness (LER and LWR) as described above arises not onlyin etching the polysilicon electrode but also in a high-k/metal gatestructure, or three-dimensional structure MOSFET (for example, a fintype FET), which is named as the structures of next generation MOStransistors.

A method for improving the etch resistance of a resist, such a processis studied in which an electron beam is applied to cure a photoresist,or vacuum ultraviolet light at a wavelength of 200 nm or less is appliedto a resist pattern obtained by development for curing. However, inthese methods, the electron beam or VUV light is applied after formingthe resist pattern, and it is difficult to bring curing effect into theinside of the resist pattern or an anti-reflective film. Thus, in theprocess of etching layers below the anti-reflective film, such atendency is observed that roughness on the surface and the side surfaceis grown to degrade LER and LWR.

According to the application of a representative processing apparatus ofthe present invention, the processing apparatus includes: an ultravioletlight applying unit including a plasma generating unit that supplieshigh frequency energy into a vacuum chamber to generate plasma; anetching unit that etches a sample brought in the processing space; avacuum side transport chamber including a transfer unit that isconnected to the etching unit and brings the sample in and out of theetching unit in a vacuum atmosphere; and an atmospheric transportchamber including a transfer unit that brings the sample in theatmosphere to the vacuum side transport chamber side through a lockchamber and brings the processed sample out of the vacuum side transportchamber side through the lock chamber for returning the processed sampleto the atmosphere. In an etching apparatus that etches a sample having asubstrate formed with an anti-reflective film and a resist thereon, thevacuum side transport chamber applies vacuum ultraviolet light to thesample for curing the resist and the anti-reflective film.

According to the application of the present invention, it is possible toprovide a plasma processing technique that can suppress roughness whichoccurs on the surface or the side surface of a photoresist film formedon a semiconductor substrate in forming interconnection patterns and canimplement highly accurate etching.

In the following, a ninth embodiment of the present invention will bedescribed with reference to the drawings. FIG. 18 is a diagramillustrating the schematic configuration of a plasma etching apparatusaccording to this embodiment. In FIG. 18, a plasma processing apparatus100 is roughly separated into a vacuum side block 101 on the upper sidein FIG. 18 and an atmosphere side block 102 on the lower side in FIG.18.

The atmosphere side block 102 includes a mounting stage 108 on whichcassettes 109 and 109′ are placed. The cassettes 109 and 109′ canaccommodate a plurality of samples to be processed by the vacuumprocessing apparatus 100. In an atmosphere side transport chamber 107, atransport chamber is disposed, which is a space into which samples to beprocessed in the cassette 109 are brought.

The vacuum side block 101 includes a vacuum side transport chamber 105disposed at the center part, and a plurality of vacuum chambers mountedon the side walls corresponding to the sides of the polygon of thevacuum side transport chamber 105 and connected thereto. On two sidewalls on the upper side of the vacuum side transport chamber 105,etching units 103 and 103′ are provided, each having a processingchamber to etch samples to be processed therein. Moreover, on the sidewall of the vacuum side transport chamber 105 on the right side in FIG.18, an ultraviolet light applying unit 104 is disposed to applyultraviolet light (an ultraviolet wavelength in a range near shortwavelengths of 10 to 200 nm in ultraviolet light) to samples to beprocessed therein. It is noted that the samples to be processed arevacuum-transported between the etching unit 103 and the ultravioletlight applying unit 104.

Between the atmosphere side transport chamber 107 and the vacuum sidetransport chamber 105, load lock chambers or unload lock chambers 106and 106′ are disposed, which are vacuum chambers to deliver samples tobe processed between atmosphere and vacuum.

It is noted that in the case of providing a unit to generate vacuumultraviolet light in the etching units 103 and 103′, it is unnecessaryto provide the vacuum ultraviolet light applying unit 104. In thisembodiment, an example that the vacuum ultraviolet light applying unitis disposed near the etching apparatus will be described.

FIG. 19 is a diagram illustrating an exemplary vacuum ultraviolet lightapplying unit. FIG. 19 is a cross sectional view illustrating anapparatus to apply vacuum ultraviolet light from plasma. In FIG. 19, thevacuum ultraviolet light applying unit is roughly separated into aplasma generating vacuum chamber 201 on the upper side and a sampleprocessing chamber 204 on the lower side. A vacuum ultraviolet lighttransmission window 203 partitions the plasma generating vacuum chamber201 and the sample processing chamber 204.

The material of the vacuum ultraviolet light transmission window 203 ismade of a material that transmits an emission wavelength shorter than anexposure wavelength, such as synthetic silica, magnesium fluoride(MgF₂), calcium fluoride (CaF₂), or lithium fluoride (LiF), for example.The plasma generating vacuum chamber 201 includes a gas supply apparatus202 that supplies a gas to be turned into plasma. Gas species to beturned into plasma may be any gas species having an emission wavelengthshorter than an exposure wavelength. For example, a mono gas such ashydrogen gas, helium gas, argon gas, hydrogen bromide gas, and nitrogengas, and a mixed gas containing these gases are used. For a plasmagenerating method in the plasma generating vacuum chamber 201, it issufficient that uniform plasma can be generated. For example, an ICP(Inductively Coupled Plasma) etching apparatus, a parallel plate plasmaetching apparatus, an ECR (Electron Cyclotron Resonance) etchingapparatus, or the like is used.

The plasma generating vacuum chamber 201 is connected with an evacuationapparatus (omitted in the drawing) through an air outlet port. Moreover,in the processing chamber 204 into which a sample to be processed isbrought, a sample fixing electrode 206 (omitted in the drawing) isprovided, including a vacuum chuck function and a heating and coolingfunction.

Furthermore, the processing chamber 204 is connected with an evacuationapparatus (omitted in the drawing) through an air outlet port as similarto the plasma generating vacuum chamber 201. Thus, in the case wherenitrogen gas is introduced into the processing chamber 204 and vacuumultraviolet light is applied in an atmosphere, it is possible to preventthe development of the deterioration or ashing of a resist caused byozone to be generated.

It is necessary that a sample to be processed is applied with vacuumultraviolet light in a vacuum preferable for resist processing, or undera preferable gas pressure. Thus, the gas supply apparatus and a pressurecontrol apparatus are disposed in the processing chamber 204 asnecessary.

In applying vacuum ultraviolet light, a sample 205 to be processed istransported to the processing chamber 204, and chucked on and fixed tothe sample fixing electrode 206, and the temperature of the samplefixing electrode is controlled to adjust the temperature of the sampleto be processed.

Subsequently, a gas is supplied from the gas supply apparatus 202 to theplasma generating vacuum chamber 201 for generating plasma. The vacuumultraviolet light generated from this plasma is applied to the sample205 to be processed through the ultraviolet light transmission window203. Thus, it is possible to reduce roughness formed on the surface orthe side surface of the photoresist.

It is noted that for another exemplary vacuum ultraviolet light applyingunit, an excimer lamp to apply vacuum ultraviolet light is used for alight source instead of plasma. In this case, a discharge tube (anexcimer lamp) is provided in an excimer lamp unit. For the dischargetube, a light source at a peak wavelength shorter than an exposurewavelength is used, such as a xenon light source (a peak wavelength of172 nm), a krypton light source (a peak wavelength of 146 nm), and anargon light source (a peak wavelength of 126 nm), for example.

In applying vacuum ultraviolet light, a sample to be processed istransported to a processing chamber, and chucked on and fixed to asample fixing electrode, and the temperature of the sample fixingelectrode is controlled to adjust the temperature of the sample to beprocessed. The processing chamber is adjusted to a vacuum preferable forthe processing of ultraviolet light application, or to a preferable gaspressure. Subsequently, vacuum ultraviolet light generated from theexcimer lamp unit is applied to the sample to be processed through anultraviolet light transmission window. Thus, it is possible to reduceroughness formed on the surface or the side surface of the photoresist.

Comparative Example

Here, a comparative example will be described.

FIG. 20 shows diagrams illustrative of an example (a comparativeexample) that plasma is used to etch a semiconductor substrate or thelike.

FIG. 20(a) is a cross sectional view illustrating a typical method forforming the gate electrode of a MOS transistor. As illustrated in FIG.20(a), a gate insulating film layer 405 is formed on a semiconductorsubstrate 406, and a gate electrode material is deposited thereon toform a conductive film layer 404. Moreover, a mask layer (a hard masklayer, for example) 403 is formed on the conductive film layer 404.Subsequently, an organic material is coated on the mask layer 403 toform an anti-reflective film (a BARC (Bottom Anti-Reflection Coating),for example) layer 402, or a BARL (Bottom Anti-Reflection Layer) isformed using an inorganic material for the anti-reflective film inexposing a photoresist. Lastly, a resist material is coated on theanti-reflective film 402 by spin coating, and a circuit pattern isexposed by projecting printing using an ArF laser or the like fordevelopment, thereby forming a photoresist mask pattern 401.

In exposure in the photolithography techniques, it is necessary todeliver an exposing light to the bottom part of a resist with sufficientintensity. However, an unnecessary portion of a photoresist material isexposed to light due to reflection at a thin film surface or irregularreflection at a step portion or the like, and ununiformity occurs inexposure. In this case, unnecessary roughness occurs on the surface orthe side surface of the circuit pattern of the photoresist formed indevelopment.

Moreover, unnecessary roughness is also formed on the surface or theside surface of the resist due to the ununiformity of resist polymersize, the aggregation of polymers, and the ununiformity of aciddiffusion in chemical amplification reactions.

FIG. 20(b) illustrates a shape after etching. In the conventionaletching method, the photoresist circuit pattern 401 formed with theroughness is used as a mask to etch under layers that is laminated thinfilms. Thus, roughness is also formed on the side surface of the etchedunder thin films as similar to the roughness formed on the surface orthe side surface of the photoresist. Furthermore, this roughness tendsto enlarge due to the contraction or expansion of the resist maskpattern caused by gas in the process of etching.

Tenth Embodiment

FIG. 21 shows diagram illustrative of an etching method according to atenth embodiment of the present invention. An example illustrated inFIG. 21 is an example that performed a process for improving roughnesson the surface or the side surface of a photoresist mask pattern 501 anda process for suppressing the growth of roughness which occurs in theprocess of etching. For the processes, a vacuum ultraviolet lightapplying apparatus disposed next to an etching apparatus is used to cureroughness with vacuum ultraviolet light in order to reduce roughness onthe photoresist mask pattern 501 and roughness on an anti-reflectivefilm 502.

FIG. 21(a) is a diagram illustrating the cross sectional structure of asample to be processed (the gate electrode of a MOS transistor 503-506),which is exposed using an exposure apparatus, and then developed forforming a resist pattern.

Subsequently, in order to reduce roughness on the surface and the sidesurface of the photoresist mask pattern 501 prior to etching the sampleto be processed, the sample to be processed is transported to the vacuumultraviolet light applying unit 104 of the plasma processing apparatus100, and vacuum ultraviolet light is applied to the entire surface ofthe resist pattern in a vacuum (FIG. 21(b)). With this vacuumultraviolet light application, roughness on the surface of thephotoresist mask pattern 501 (a hatched portion in FIG. 21(b)) androughness on the surface of the anti-reflective film 502 (a hatchedportion in FIG. 21(b)) are improved.

Subsequently, the sample to be processed is vacuum-transported from thevacuum ultraviolet light applying unit 104 to the etching unit 103, andthe anti-reflective film 502 is etched.

It is noted that in the case of forming a desired circuit pattern byplasma etching, with the downscaling of LSI, a circuit pattern indimensions smaller than the dimensions of a photoresist material thatcan be exposed has to be formed.

For a method of obtaining a circuit pattern in dimensions smaller thanexposure critical dimensions using an exposure apparatus, a trimmingprocess is used for the purpose of forming a mask pattern in maskdimensions smaller than an exposed, developed photoresist pattern inplasma etching. This trimming process is also called a slimming processor a shrinking process, and the trimming process is generally performedbefore etching the anti-reflective film or after etching theanti-reflective film.

FIG. 21(c) illustrates a cross sectional structure after etching andtrimming the anti-reflective film. The surface of the photoresist maskpattern 501 and the surface of the anti-reflective film 502 cured withvacuum ultraviolet light in FIG. 21(b) are removed by etching andtrimming the anti-reflective film. Thus, in the case where laminatedfilms under a mask layer 503 are etched in the state in FIG. 21(c),there is a problem in that roughness again occurs due to the contractionor expansion of the resist mask pattern 501 or the anti-reflective film502 caused by an etching gas.

For this problem, after etching and trimming the anti-reflective film,the sample to be processed is again transported from the etching unit103 to the vacuum ultraviolet light applying unit 104, and vacuumultraviolet light is applied to the entire surface of the resist patternin a vacuum (FIG. 21(d)). With this vacuum ultraviolet lightapplication, the resist mask pattern 501 and the anti-reflective film502 are cured with vacuum ultraviolet light to the inside thereof. Afterapplying vacuum ultraviolet light, the sample to be processed is againvacuum-transported from the vacuum ultraviolet light applying unit 104to the etching unit 103 for etching laminated films under the mask layer503.

Thus, the transfer of roughness formed on the surface or the sidesurface of the resist mask pattern 501 and the growth of roughness inthe etching process are suppressed, and roughness (LER) on the line sidesurface or the roughness of line width (LWR) is reduced.

It is noted that the etching unit 103 and the vacuum ultraviolet lightapplying unit 104 are connected to each other in vacuum transport. Thus,it is possible to suppress the deterioration of the sample surface aftervacuum ultraviolet light application due to unnecessary oxidation or thelike, and it is possible to expect the effect of reducing LER and LWR inetching.

FIG. 22 is a diagram illustrating the effect of vacuum UV applicationaccording to this embodiment. FIG. 22 illustrates the depth directionprofile of a main chain component of an organic polymer forming a resistmaterial, and the profile is obtained by time-of-flight secondary ionmass spectrometry (TOF-SIMS). The left side of a dotted line in FIG. 22is a resist surface, and the right side in FIG. 22 is a resist deepportion. In FIG. 22, 601 expresses a sample applied with no vacuumultraviolet light, and 602 expresses a sample applied with vacuumultraviolet light at an accumulated illuminance of 2.0 mJ/cm².

As apparent from FIG. 22, in the case of applying no vacuum ultravioletlight, the structure of the main chain component of the organic polymeris not changed in the resist depth direction. In contrast to this, itwas confirmed that in the sample applied with vacuum ultraviolet lightat an accumulated illuminance of 2.0 mJ/cm², the main chain component ofthe organic polymer forming the resist material is gradually reducedfrom a deep portion to the surface (the main chain structure isdecomposed to the deep portion). It is noted that the similar result wasconfirmed also on the anti-reflective film.

From this result, a cause can be considered that applying vacuumultraviolet light to the resist mask pattern and the anti-reflectivefilm, that is, applying wavelength light with photon energy higher thanthe binding energy of various molecules contained in the organic polymerforming the resist and the anti-reflective film (C—C bond, C═C bond, C—Obond, C═O bond, and C—H bond, for example) promotes the decomposition ofthe main chain component, and relaxes the contraction or expansion ofthe organic polymer forming the resist and the anti-reflective film dueto an etching gas (the organic polymer film is improved and reinforced).

FIG. 23 is a diagram illustrative of the effect given to line widthroughness (LWR). In FIG. 23, the horizontal axis expresses processsteps, and the vertical axis expresses a LWR value.

First, (1) in the case where first and second vacuum ultraviolet curingprocesses are not performed on the resist mask pattern and theanti-reflective film (701), roughness formed on the surface and the sidesurface of the resist mask pattern is transferred to the anti-reflectivefilm. Moreover, this roughness causes the contraction or expansion ofthe organic polymer forming the resist and the anti-reflective film inetching and trimming the anti-reflective film and in etching underlayers, and is transferred to the side surface of the gate electrode inan enlarged form.

(2) In the case where only the first vacuum ultraviolet curing processis performed on roughness formed on the surface and the side surface ofthe resist mask pattern (702), although LWR is reduced after the firstvacuum ultraviolet curing process, the contraction or expansion of theorganic polymer forming the resist and the anti-reflective film occursin later etching and trimming the anti-reflective film and etching underlayers, and roughness is enlarged and transferred to the side surface ofthe gate electrode.

(3) In the case where the first vacuum ultraviolet curing process isperformed on the surface and the side surface of the resist mask patternand the second vacuum ultraviolet curing process is performed afteretching and trimming the anti-reflective film (703), in this case, thecontraction or expansion of the organic polymer forming the resist andthe anti-reflective film is suppressed also in etching under layers inaddition to in etching and trimming the anti-reflective film. Thus,roughness formed on the surface and the side surface of the resist maskpattern is not transferred, and roughness is not grown in the process ofetching, thereby greatly reducing LER and LWR that occur on the sidesurface of the gate electrode.

As described above, according to this embodiment, in etching a sample tobe processed with thin films (a gate insulating film, a conductive film,and a mask layer) laminated on a semiconductor substrate, ananti-reflective film formed on the thin films, and a photoresist maskpattern formed on the anti-reflective film for forming a gate electrode,for example, vacuum ultraviolet light generated from plasma or anexcimer lamp is applied before etching the mask pattern and afteretching the anti-reflective film to cure the mask pattern and theanti-reflective film for reducing roughness (LER and LWR) on the surfaceor the side surface of the mask pattern and the anti-reflective film,and then the mask pattern is used to plasma-etch the laminated thinfilms below the mask pattern. Thus, it is possible to perform highlyaccurate etching, and it is possible to manufacture highly accuratesemiconductor devices.

It is noted that in the examples above, the case is described where thevacuum ultraviolet light applying apparatus provided with the plasmagenerating mechanism or the excimer lamp is disposed near the etchingapparatus that can vacuum-transport samples. However, the similar effectcan also be obtained in the case where a similar ultraviolet lightapplying apparatus is provided in the etching apparatus.

Moreover, an example is taken and described in which the gate electrodeof the MOS transistor is etched. However, the similar effect can beobtained also in the manufacturing processes for thin film materials andsemiconductors showing similar characteristics. Furthermore, in thisembodiment described above, the effect is described on the etchingprocess in the front-end process of semiconductor devices. However, thesimilar effect can also be obtained by applying this embodiment toetching techniques in the back end process of semiconductor devices(wiring connection and super connect), micro machines, and the fields ofMEMS (the fields of displays, optical switches, communications,storages, sensors, imagers, small-sized generators, small-sized fuelbatteries, micro probers, and processing gas control systems, includingthe field related to the field of medical and biotechnology), and so on.

Eleventh Embodiment

FIG. 24A is a vertical cross sectional view illustrating the essentialpart of a sample processing apparatus with VUV light (vacuum ultravioletlight) using a plasma light source according to an eleventh embodimentof the present invention. FIG. 24B is a diagram illustrative of theoperation of the sample processing apparatus according to the eleventhembodiment.

A VUV transmission filter 24 is made in which the VUV transmissionfilter 24 can be transported between a holding surface 82 of a filterholder 27 in a vacuum ultraviolet light applying unit 104 and a vacuumside transport chamber 105 using a wafer transfer robot (omitted in thedrawing) or the like for exchanging the VUV transmission filter 24. InFIGS. 24A and 24B, numeral 80 is a chamber, 81 is filter transferdirection, 87 is a silica shower plate, 811 is a wafer mountingelectrode, 814 is an evacuation apparatus, 828 is a vertical motionmechanism, and 853 is a push-up pin.

Alternatively, such a configuration may be possible in which a holder(omitted in the drawing) that can hold a plurality of the VUVtransmission filters 24 is provided to exchange the VUV transmissionfilter 24. These methods allow the VUV transmission filter 24 to beexchangeable, whereby the VUV transmission filter 24 can be exchanged.without exposing the VUV transmission filter 24 to air even in the casewhere the VUV light transmission characteristics are degraded due to thecontamination or the like of the VUV transmission. filter 24. Thus,there is the effect that it is possible to improve throughput and toprocess a wafer 15 with VUV light in excellent reproducibility.

REFERENCE SIGNS LIST

-   1 Magnetron-   2 Rectangular waveguide-   3 Matching unit-   4 Circular waveguide-   5 Cavity resonator-   6 Silica plate-   7 Silica shower plate-   8 Chamber-   9 Gas pipe-   10 Exhaust velocity variable valve-   11 Wafer mounting electrode-   12 Exhaust duct-   13 Open and close valve-   14 Evacuation apparatus-   15 Wafer-   16 VUV light the processing space-   17 Plasma generating space-   18 Coil-   19 Coil-   20 Yoke-   21 Rectangular-to-circular converter-   23 High frequency power supply-   24 VUV transmission filter-   25 Gas outlet port-   26 Gas inlet port-   27 Movable side wall-   28 Vertical motion mechanism-   29 A high frequency power supply-   30 A high frequency coil-   31 Cover-   50 Heating and cooling mechanism-   53 Push-up pin-   54 Filter holder-   101 A vacuum side block-   102 An atmosphere side block-   103 Etching units-   104 An ultraviolet light applying unit-   105 Wafer-   106 Wafer stage-   300 Control unit-   301 Chamber internal pressure adjusting unit-   302 Power supply control unit-   303 Gas supply control unit-   304 VUV transmission filter position control unit-   305 Transfer unit-   310 Controller.

The invention claimed is:
 1. A sample processing apparatus comprising: achamber; a plasma generating space disposed inside the chamber, theplasma generating space being configured for plasma to be generated inthe chamber; a processing space disposed inside the chamber to be atleast partially surrounded by the plasma generating space, wherein theprocessing space is configured for a sample to be processed in theprocessing space using the plasma for a light source; a VUV transmissionfilter disposed between the plasma generating space and a stage whichincludes a sample mounting surface on which the sample to be processedis placed; a holding device configured to hold the VUV transmissionfilter and to move the VUV transmission filter vertically above thestage, and such that the holding device with the VUV transmission filtercan be supported on the stage; and an evacuation unit configured toevacuate the plasma generating space and the processing space to reducepressure inside thereof after the VUV transmission filter has beenlifted to a predetermined position by the holding device, wherein: theprocessing space is enclosed by the stage, the holding device and theVUV transmission filter, the VUV transmission filter faces the plasmagenerating space and is disposed above the stage so as to cover thesample mounting surface, and is configured to enable a fluidcommunication between the processing space and the plasma generatingspace in the chamber after the VUV transmission filter has been liftedto a predetermined position by the holding device; and the VUVtransmission filter is configured to transmit VUV light including awavelength of 200 nm or less included in the plasma light source.
 2. Thesample processing apparatus according to claim 1, wherein the VUVtransmission filter is configured to block electrons, ions, and radicalsincluded in the plasma.
 3. The sample processing apparatus according toclaim 1, wherein an outer diameter of the VUV transmission filter islarger than an outer diameter of the sample, and a height of theprocessing space is 5% or less of the outer diameter of the VUVtransmission filter.
 4. The sample processing apparatus according toclaim 1, wherein the VUV transmission filter is comprised of any onematerial of synthetic silica, MGF₂, CaF₂, LiF, and sapphire.
 5. Thesample processing apparatus according to claim 1, wherein the plasmagenerating space is configured to receive a gas supplied to the plasmagenerating space, which comprises an inert gas , a nondepositional gas,or a mixed gas of the inert gas and the nondepositional gas, wherein theinert gas comprises any one of Ar, Xe, He, Ne, and Kr, and wherein thenondepositional gas , comprises any one of HBr, HCI, N₂, O₂, H₂, SF₆,and NF₃.
 6. The sample processing apparatus according to claim 1,comprising: a gas introducing unit configured to introduce gas into theprocessing space, wherein the introduced gas includes N₂, an inert gas,SF₆, Cl₂, HBr, O₂, CF₄, or a mixed gas of these gasses.
 7. The sampleprocessing apparatus according to claim 1, comprising: a correcting unitconfigured to correct a light quantity in-plane distribution of VUVlight from the plasma light source applied to the sample to be processedat a wavelength of 200 nm or less.
 8. The sample processing apparatusaccording to claim 7, wherein the correcting unit is made of a VUVtransmission material and configured to correct an in-plane lightintensity distribution of VUV light by changing a thickness of the VUVtransmission material in a plane so that the in-plane light intensitydistribution becomes a desired in-plane light intensity distribution. 9.The sample processing apparatus according to claim 7, wherein thecorrecting unit is made of a material that does not transmit VUV lightsuch as a metal plate, a ceramics plate, a glass plate, or a Si plate,and has a plurality of openings having a through mesh structure or athrough hole structure; and the correcting unit corrects an in-planelight intensity distribution of VUV light by changing an in-planedistribution of an aperture ratio of the openings so that the in-planelight intensity distribution becomes a desired in-plane light intensitydistribution.
 10. The sample processing apparatus according to claim 7,wherein the correcting unit corrects an in-plane light intensitydistribution of VUV light according to a plasma generating condition anda material of the plasma light source.
 11. The sample processingapparatus according to claim 1, wherein the VUV transmission filter isexchangeable using a transfer mechanism or a plurality of holdermechanisms.
 12. The sample processing apparatus according to claim 1,wherein the VUV transmission filter is provided with a temperatureadjusting function such as a cooling function.
 13. The sample processingapparatus according to claim 1, wherein the processing space isconfigured to be decompressed for the VUV light processing.
 14. Thesample processing apparatus according to claim 1, comprising: a gasintroducing unit configured to introduce, into the processing space, aninert gas, a process gas, or a mixed gases of the inert gas and theprocess gas.
 15. The sample processing apparatus according to claim 14,wherein the process gas includes any one of SF₆, Cl₂, HBr, O₂, and CF4.16. The sample processing apparatus according to claim 1, wherein saidholding device is comprised of an annular movable sidewall locatedbetween the stage and the VUV transmission filter.